Browsing by Creator "Rosen, Alexander"
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Item Investigation on the Synthesis, Application and Structural Features of Heteroaryl 1,2-Diketones(2022-08-02) Wehrle, Robert J.; Rosen, Alexander; Nguyen, Thu Vu; Koons, Kalyn; Jump, Eric; Bullard, Mason; Wehrle, Natalie; Stockfish, Adam; Hare, Patrick M.; Atesin, Abdurrahman; Ateşin, Tülay A.; Ma, LiliA set of unsymmetrical heteroaryl 1,2-diketones were synthesized by a heteroarylation/oxidation sequence with up to 65% isolated yields. Palladium catalyst XPhos Pd G4 and SeO2 were the key reagents used in this methodology, and microwave irradiation was utilized to facilitate an efficient and ecofriendly process. The application of heteroaryl 1,2-diketones is demonstrated through the synthesis of an unsymmetrical 2-phenyl-3-(pyridin-3-yl)quinoxaline (5a) from 1-phenyl-2-(pyridin-3-yl)ethane-1,2-dione (4a). The lowest energy conformations of 4a and 5a were located using Density Functional Theory (DFT) at the M06-2X/def2-TZVP level of theory. Two lowest energy conformations of 4a differ with respect to the position of the N atom in the pyridyl ring and 0.27 kcal/mol energy difference between them corresponds to 60.4 and 39.6% at 50 °C in toluene. Four lowest energy conformations for 5a have the energy differences of 0.01, 0.03 and 0.07 kcal/mol that corresponds to 26.0, 25.7, 24.9 and 23.4%, respectively. A comparison of 4a and 5a to the less hindered analogs (oxalyl chloride and oxalic acid) is used to investigate the structural features and bonding using Natural Bond Orbital (NBO) analysis.Item Palladium-Catalyzed Direct α‑C(sp3) Heteroarylation of Ketones 2 under Microwave Irradiation(American Chemical Society, 2019-04-19) Quillen, Andrew; Nguyen, Quynh; Neiser, Matthew; Lindsay, Kara; Rosen, Alexander; Ramirez, Stephen; Costan, Stefana; Johnson, Nathan; Do, Thuy Donna; Oscar, Rodriguez; Rivera, Diego; Atesin, Abdurrahman; Ateşin, Tülay Aygan; Ma, LiliHeteroaryl compounds are valuable building blocks in medicinal chemistry and chemical industry. A palladium-catalyzed direct α-C(sp3) heteroarylation of ketones under microwave irradiation is developed and reported in this study. Under optimized conditions, twentyeight (28) heteroarylated ketones were prepared in this study to demonstrate the substrate scope of this reaction. The ground-state optimized structure of Pd(0) active catalyst with 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (XPhos) in toluene, and the products of its reaction with 3-bromopyridine and acetophone were studied using all-atom density functional theory. This study provided insightful information for palladium catalytic system design to generate heteroaryl compounds.